July 25 – Hey, Eddie!

Today’s factismal: Reptiles are found on every continent except Antarctica (and they used to live there!).

If you want to call a group of animals successful, then you have your choice of how to define the term. You can base it on the distribution of the critters: those that live in more places are more successful. Or you can base it on the longevity of the critters’ clade: those that have been around longer are more successful. Or you can base it on all of the other critters that have evolved out of that clade: having more branches on their tree of life makes them more successful. But no matter how you define success, the reptiles have it.

An alligator in Texas (My camera)

An alligator in Texas
(My camera)

They are found on every continent except Antarctica and used to live there until it got too cold for them about 15 million years ago. Reptiles are found in a wide variety of environments, from the rocky shores of the Galapagos to the lush rain forests of North America. They eat an incredible variety of foods, from salty seaweed to juicy grubs to each other. And the reptiles have been around for a long, long time; the earliest known reptile lived some 338 million years ago. But most importantly, they gave rise to a wide variety of other types of animals, from the dinosaurs (who gave rise to the birds) to the mammals (who gave rise to us and the internet).

An iguana in Florida (My camera)

An iguana in Florida
(My camera)

But success has its price. In the case of the reptiles, it means getting pushed out by younger and more vigorous critters, like humans. In Los Angeles and other parts of California, the native lizards have almost entirely disappeared, thanks to changes in the environment caused by building and water use. It has gotten so bad that now researchers are out looking for lizards, and they’d like your help. If you happen to live in Los Angeles (or are just stuck in a tourist trap ☺), then why not give them a hand by reporting any lizards that you see to the RASCals Project at the Los Angeles Natural History Museum:

July 24 – Light Of My Life

Today’s factismal: Many experts can identify animals by the color of their “eyeshine”, the light reflected by their eyes.

Shine a light outside at night and you are almost certain to see something startling: two glowing dots staring back at you. Even when the light is too faint to reveal the animal’s shape, you can still see those eerie glowing dots. But why should an animal’s eyes shine in the dark? And why can some people tell which animal it is just from the color of the reflection?

Eyeshine from a zebra (Image courtesy Instant Wild)

Eyeshine from a zebra
(Image courtesy Instant Wild)

That reflected light is known as eyeshine, and not all animals have it; for example, humans don’t have eyeshine, nor do squirrels. In general, most diurnal animals don’t have eyeshine and most nocturnal animals do (though exceptions abound on both sides). And that is the reason for the eyeshine: it is caused by a reflecting layer known as the tapetum lucidum (“bright tapestry” in geek-latin). That layer bounces light that passes through the retina back for another pass, and increases the eye’s sensitivity in low light situations (i.e., at night). But, evolution being what it is, the tapetum lucidum isn’t the same in all nocturnal animals. In some animals, it is made up of a layer of guanine crystals. In others, it is parallel fibers. And in yet others, it is a mish-mash of different structures. And that’s why different species have different colors of eyeshine; the tapetum lucidum reflects light back, but the color of the light that gets reflected back depends on the type of the tapetum, just as the color reflected off of a wall depends on the color of the wall. As a result, owls and other birds have red eyeshine, as do foxes and rabbits. But cats and frogs have a greenish eyeshine, and raccoons have yellow eyeshine.

Eyeshine from coyotes (Image courtesy Instant Wild)

Eyeshine from coyotes
(Image courtesy Instant Wild)

Now this is more than just a fun way to identify animals at night; it is also a way to identify animals in night-time cameras, like those at Instant Wild. They’ve got a collection of photos taken by camera traps across the globe, and they need your help in identifying the animals. To pitch in (and see some great examples of eyeshine), set your browser to:

July 23 – Bird’s Eye View

Today’s factismal: The first Landsat was launched 42 years ago; we are now up to Landsat 8.

Look! Up in the sky! It’s a bird! It’s a plane! It’s Landsat!

The first Landsat (Image courtesy USGS)

The first Landsat
(Image courtesy USGS)

If you ask any geologist or oceanographer what the most successful satellite program ever is, odds are that they’ll tell you it is Landsat. The program started in 1966, when scientists realized that using different colors of light (a trick known as multispectral scanning) could help them see the world in a new way. But the colors that they used weren’t red, green, and blue; instead, they used colors like infrared and ultraviolet. Though the human eye can’t see those colors, many plants can. They either absorb the energy for use in creating sugars or reflect it to attract insects and other pollinators. So by using these unusual colors of light, the scientists were able to map out where plants were growing and what the soil and rocks look like better than just using visible light would allow.

A four color image taken by Landsat (Image courtesy USGS)

A four color image taken by Landsat
(Image courtesy USGS)

But it took time to develop sensors that were good enough and small enough to fit into a satellite – six years of time, to be exact. The first Landsat was launched in 1972, and proved to be an immediate success. Though it only recorded 1,692 images, they were something special. In those images, Landsat discovered new islands and showed forests being logged and the remains of ancient cities.

The first image taken by Landsat (after a lot of processing), showing Dallas, TX (Image courtesy USGS)

The first image taken by Landsat (after a lot of processing), showing Dallas, TX
(Image courtesy USGS)

Since that original launch, seven more Landsats have been launched (though only six made it to orbit). And the current edition, Landsat 8, was put into orbit just over a year ago and is giving us amazing new images of the Earth. If you’d like to help put those new images to good use, then why not join the Geo-Wiki Project? They want to improve land cover maps using resources such as Landsat. To join, head on over to:

July 22 – Feeling Crabby

Today’s factismal: Live mitten crabs are sold by vending machines in Chinese subways.

The mitten crab is an ugly critter. They get their name from the hairs that cover their claws, making it look as if they are wearing mittens, but that isn’t their worst feature. They have four sharp spines on their bodies, but that isn’t their worst feature, either. They have sharp, pointy legs for walking on the bottom (they don’t swim), but that still isn’t their worst feature. What is their worst feature? That they are invading Europe and North America.

A mitten crab (Image courtesy Mitten Crab Watch)

A mitten crab
(Image courtesy Mitten Crab Watch)

These crabs are native to Asia, where they are a popular delicacy. Mitten crabs are so popular there that they are sold through vending machines and are seen on many restaurant menus; the crabs from some areas can fetch upwards of $50 per pound. They are traditionally served with ginger and vinegar, and are eaten through the latter part of the year. More than 200,000 tons of mitten crab worth more than $1.2 billion are eaten every year in China. Indeed, mitten crabs may be too popular in China; they are now a rare sight in many parts of their traditional range.

A mitten crab (Image courtesy Mitten Crab Watch)

A mitten crab
(Image courtesy Mitten Crab Watch)

Unfortunately, they are becoming an all too common sight on the coasts of North America where they were introduced by freighters discharging their ballast water. First spotted in San Francisco bay in 1922, they now are found as far north as Portland and as far south as San Diego; they have also been spotted in Boston and Baltimore on the East coast. Mitten crabs eat fish roe and the larvae of other crabs, reducing native species; they also burrow into the banks of estuaries, causing local collapse and damaging dams and flood control projects. Some estimate their annual damage at more than $80 million.

Fortunately, there is a simple solution to the mitten crab invasion: eat them! In California, you are allowed to catch up to 35 mitten crabs each day; similar rules apply in Oregon and Maryland. But, before you dig out the butter and Old Bay, be sure to take a picture of the critter and send it to the researchers at Mitten Crab Watch. They are trying to track the mitten crab so that we can discover other ways to control the invaders. (You might also use the website as a way to find the best places to go crabbing.)

July 21 – Too Low For Zero

Today’s factismal: The lowest recorded naturally occurring temperature was 128.6 °F below zero; it happened at Vostok Station in Antarctica in 1983.

When it comes to low temperatures, there’s chilly, down right cold, and “Whoa!”. And in 1983, Vostok Station in Antarctica definitely fell into the third category. Then again, even when it is warm at Vostok Station, it is down right cold. That’s because Vostok Station is located in the middle of Antarctica where cold temperatures are just a fact of life.

The monthly average high and low temperatures for Vostok Station, Antarctica (Brr!)

The monthly average high and low temperatures for Vostok Station, Antarctica (Brr!)

But it turns out that those cold temperatures may have an upside. You see, Antarctica is covered with glaciers. And some of those glaciers just happen to cover lakes that are kept liquid either by having exceptionally high salt contents or by being near a geothermal heat source; these are known as Antarctica’s subglacial lakes. And the largest known subglacial lake just happens to be very near Vostok Station, which is why it is called Lake Vostok.

The Lake Vostok drilling campaign (Image courtesy Nature)

The Lake Vostok drilling campaign
(Image courtesy Nature)

You may have heard of the lake, because it has been in the news a lot. A science team spent more than a decade drilling through the ice to reach the lake. Their hope is that, because the lake has been sealed off by glaciers for some 15 million years, they will discover either fish and other critters that have evolved separately from those everywhere else or (and here’s the exciting part) they will find completely new critters that will tell us if we might find life elsewhere in the Solar System. Thus far, though, what they’ve discovered is that ordinary life is pretty resilient and can survive in places (like Lake Vostok) where you would think it couldn’t. Of the 3,500 gene sequences that they’ve discovered thus far, the vast majority appear to belong to critters found in other lakes. Believe it or not, this is an exciting result with lots of interesting implications for evolution and life on other planets (maybe we’ll find Mr. Spock after all!).

What is known for sure is that it is amazing that anything could actually live in a lake that is in perpetual darkness, under a pressure equal to 350 atmospheres, and is so full of oxygen and nitrogen that the water would bubble if it were brought to the surface. And the other thing that is known for sure is that once the critters from Lake Vostok are identified, they’ll make their way into the Encyclopedia of Life. It is a free on-line resource that lists every known animal, plant, protist, or politician (wait; I’ve just been informed that politicians are not considered to be life forms). If you’d like to check it out, look here:

July 14 – The Friendly Red Planet

Today’s factismal: The first close-up images of Mars were sent by Mariner 49 years ago today.

Mars has always fascinated people, from the days when the Bablyonians called it Nergal and blamed it for catastrophes like war, famine, and single-party tickets. Today we don’t blame Mars for our disasters (though we do wonder about the Great Galactic Ghoul) but we are still as fascinated as ever. Is there life on Mars? Can people live on Mars? How many illudium 36 explosive space modulators do they have?

Though the last question is a little silly, the other two are quite serious. In the 1800s, telescopes had finally improved enough for people to see Mars as something more than just a blurry dot; it was now a big, blurry dots. And when people (like Giovanni Schiaparelli and Percival Lowell) see blurry things, they tend to describe things that may or may not actually be there, like the canals of Mars. And those things that get described can lead people to do all sorts of crazy things (like panic over a Halloween joke)

Percival Lowell's drawing of the martian canals (Image courtesy Percival Lowell)

Percival Lowell’s drawing of the martian canals
(Image courtesy Percival Lowell)

The first close-up picture of Mars (Image courtesy NASA)

The first close-up picture of Mars
(Image courtesy NASA)

The only way to stop the panic is to get a good view of what is actually on Mars and the only way to do that is to go there. And, in 1965, that’s exactly what we did. We sent a probe called the Mariner 4 to Mars, where it sent back 22 close-up images; the first images of the red planet. Though none of the images would win an award today, in 1965, they had an Earth shattering effect (but there was no ka-boom). They showed that the Earth wasn’t alone and that there were other planets where people might live.

A close-up of a crater on Mars (Image courtesy NASA's HiRISE)

A close-up of a crater on Mars
(Image courtesy NASA’s HiRISE)

The exploration of Mars continues today. And today they are taking pictures using cameras like the HiRISE (High Resolution Imaging Science Experiment), an orbiting camera that could see a martian newspaper laid out on the ground. If you’d like to take part in the exploration, why not head over to NASA’s HiRISE Public Suggestion Page to tell them where you think the next pictures should be taken, or just to glory in all of the amazing images that have already been captured.

July 13 – Under Stress

Today’s factismal: Eugène Freyssinet, father of the modern highway, was born 135 years ago today.

If you’ve ever looked at a highway overpass being built, then you’ve probably wondered “what are those wires in the concrete and why are they there?” The wires sticking out of the concrete are called tension cables and are there to make the concrete stronger by squeezing it. And the engineer who first figured out why they should be there was named Eugène Freyssinet.

Without prestressed concrete, this is what our highways would look like (Image courtesy Pont du Gard)

Without prestressed concrete, this is what our highways would look like
(Image courtesy Pont du Gard)

Large bridges are nothing new. The Romans had aqueducts (large canals to carry water) that stood 160 ft high and stretched more than 1,000 ft. But their bridges were built from brick and mortar and literally required tons of material in order to keep from breaking apart from the sheer weight of the top sections. If you look at the Brooklyn Bridge, you can see how little had changed in the world of construction between the time of the Romans and the 1800s.

Tension wires sticking out of a prestressed concrete arch; without them, the arch would fall apart. (My camera)

Tension wires sticking out of a prestressed concrete arch; without them, the arch would fall apart.
(My camera)

The reason that large bridges (and buildings and monuments, for that matter) needed so much stone was because most things are very weak when they are being pulled apart (are in tension) but are much stronger when they are being squeezed together (in compression). To understand this, consider the difference between a small pile of sand that you can easily deform with a finger and the same pile of sand stuffed into a rubber balloon where it takes a lot more strength to change its shape.

Though a lot of people knew about this effect, it took Eugène Freyssinet to develop a way of applying it to the real world. He discovered that by stretching wires out and casting the concrete around them, he could prestress the concrete and make it much stronger. As a result, he was able to build bridges that were longer and stronger than anything that was ever done before.

The TWA Flight Center at JFK (Image courtesy Ton Stam)

The TWA Flight Center at JFK
(Image courtesy Ton Stam)

And his discovery wasn’t limited to bridges. If you’ve ever seen the TWA Flight Center at JFK airport, or the LAX airport, or the Sydney Opera House, then you have seen prestressed concrete at work.

If you’d like to explore more, or search through thousands of other science topics, then why not look over the National Science Data Library? It is a free website with education plans for teachers and fun facts for everyone else!